[Interest of allergy tests in urticaria].

Urticaria is a common skin disease that may affect 20 % of the general population. Most of the time, urticaria is an acute disorder that rarely can be chronic. The difficulty in urticaria is not the clinical diagnosis because the rash is characteristic, but the underlying causes and treatment that result. Urticaria is a benign disease when chronic and potentially dangerous when acute and associated with allergy. This allergy risk, needs an allergy exploration, based on skin tests and / or specific IgE assays. Because allergy is unusual in chronic urticaria, no allergy tests should be performed. By contrast, these tests must be undertaken in case of acute urticaria with a strong suspicion of IgE-mediated reaction because of the risk of severe anaphylaxis in case of allergenic re-exposure.